Cooling apparatus for electronic devices

ABSTRACT

Disclosed herein is a cooling device primarily for cooling integrated circuits or other electronic devices during operation. The cooling device may include a heat sink portion and a fan, or other air movement device. The outer periphery of the heat sink portion may be formed with outwardly extending lobes, leaving recessed areas between the lobes. The lobes may be sized and located so as to correspond to heat concentration areas on an electronic device package. In this manner, heat sink material may be concentrated adjacent heat concentration areas where more heat removal is required. The overall mass and size of the heat sink portion may, thus, be reduced without significantly impairing the ability of the cooling device to remove heat from an electronic device.

FIELD OF THE INVENTION

The present invention relates generally to cooling devices and, moreparticularly, to a cooling device for removing heat from an electronicdevice.

BACKGROUND OF THE INVENTION

Electronic devices, such as integrated circuit devices, are increasinglybeing used in modern applications. One prevalent example is thecomputer. The central processing unit or units of most computers,including personal computers, is constructed from an integrated circuitdevice.

During normal operation, electronic devices generate significant amountsof heat. If this heat is not continuously removed, the electronic devicemay overheat, resulting in damage to the device and/,or a reduction inoperating performance. In order to avoid such overheating, coolingdevices are often used in conjunction with electronic devices.

One such cooling device is a fan assisted heat sink cooling device. Insuch a device, a heat sink is formed of a material, such as aluminum,which readily conducts heat. The heat sink is usually placed on top ofand in contact with the electronic device. Due to this contact, heatgenerated by the electronic device is conducted into the heat sink andaway from the electronic device.

The heat sink may include a plurality of cooling fins in order toincrease the surface area of the heat sink and, thus, maximize thetransfer of heat from the heat sink into the surrounding air. In thismanner, the heat sink draws heat away from the electronic device andtransfers the heat into the surrounding air. An example of a heat sinkis disclosed in U.S. Pat. No. 5,794,685 of Dean for HEAT SINK DEVICEHAVING RADIAL HEAT AND AIRFLOW PATHS, which is hereby incorporated byreference for all that is disclosed therein.

In order to enhance the cooling capacity of a heat sink device, anelectrically powered fan is often mounted within or on top of the heatsink. In operation, the fan causes air to move over and around the finsof the heat sink device, thus cooling the fins by enhancing the transferof heat from the fins into the ambient air. An example of a heat sinkdevice including a fan is disclosed in U.S. Pat. No. 5,785,116 of Wagnerfor FAN ASSISTED HEAT SINK DEVICE, which is hereby incorporated byreference for all that is disclosed therein.

Over the years, as the power of electronic devices has increased, so hasthe amount of heat generated by these devices. In order to adequatelycool these higher powered electronic devices, cooling devices withgreater cooling capacities are required. There is also an increasingtrend to package electronic devices in multi-electronic device packages.This multi-electronic device arrangement presents an additionalchallenge with respect to cooling since it results in several heatsources being located within one package. Since each of the electronicdevices in the package represents a heat emission source, each must becooled. In order to adequately cool these multiple electronic devicepackages, a cooling device must be large enough to contact, or be inclose proximity to, all of the electronic devices within the package.Accordingly, cooling devices for cooling such multiple electronic devicepackages typically are relatively large. Such large cooling devices areproblematic in that they are relatively expensive, heavy, and ofteninefficient.

Another problem with fan assisted heat sink cooling devices is the noisegenerated by the fans, particularly in situations where larger and/ormultiple fans are used to achieve increased cooling capacity. This isparticularly a problem in desktop computers where a user is commonly inclose proximity to the machine. The problem is further aggravated insituations where multiple electronic devices, and, thus, multiplecooling devices, are mounted in the same computer case, as occurs inmany high power computers.

Thus, it would be generally desirable to provide an apparatus and methodwhich overcome these problems associated with cooling devices.

SUMMARY OF THE INVENTION

Disclosed herein is a cooling device primarily for cooling integratedcircuits or other electronic devices during operation.

The cooling device may include a heat sink portion having a chambertherein. A fan, or other air movement device may be housed within thechamber. A plurality of slots, defining vanes therebetween, may extendbetween the chamber and the exterior of the heat sink. The outerperiphery of the heat sink portion may be formed with outwardlyextending protrusions, leaving recessed areas between the protrusions.The protrusions may be sized and located so as to correspond to heatconcentration areas on an electronic device package. The recessed areas,on the other hand may be located so as to correspond to areas on theelectronic device package which are not heat concentration areas. Inthis manner, heat sink material may be concentrated adjacent to heatconcentration areas where more heat removal is required. The overallmass and size of the heat sink portion may, thus, be reduced withoutsignificantly impairing the ability of the cooling device to remove heatfrom an electronic device.

The heat sink protrusions may, for example, be of generally circularshape. Alternatively, the protrusions may be formed having any othershape, such as a rectangular or a triangular shape. Although theprotrusions may be formed having any shape, they may alternatively bereferred to herein simply as “lobes”.

The heat sink chamber may include a lower wall portion which is locatedbeneath the fan blades when a fan is installed within the chamber. Thislower wall portion may slope away from the fan blades in a radiallyoutward direction. In this manner the distance between the fan bladesand the chamber lower wall portion is increased in areas where the fanblades rotate at the highest velocity. It has been found that thisincreased distance results in reduced noise emission from the coolingdevice when the fan is in operation.

The heat sink fan chamber may include a wider portion at its upper end,thus causing at least a portion of the outer wall of the fan chamber tohave an increased spacing from the fan blades. This increased spacinghas also been found to reduce noise emission from the cooling devicewhen the fan is in operation. The slots in the heat sink portion mayeither be radially oriented or may be offset slightly from the radialdirection in order to further reduce noise emission.

The cooling device may be attached to an electronic component byproviding either integrally formed attachment feet or by using a bracketarrangement. In the case where a bracket arrangement is used, thebracket may be either integrally formed with the heat sink portion ormay be a separate assembly.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a top plan view of an electronic device package.

FIG. 2 is a front elevation view of the electronic device package ofFIG. 1.

FIG. 3 is top perspective view of a cooling device mounted on theelectronic device package of FIG. 1.

FIG. 4 is a top plan view of a heat sink of the cooling device of FIG.3.

FIG. 5 is a cross-sectional elevation view taken along the line 5—5 inFIG. 4.

FIG. 6 is a side elevation view as viewed from the top of FIG. 4.

FIG. 7 is side elevation view as viewed from the right side of FIG. 4.

FIG. 8 is bottom plan view of the heat sink of FIG. 4.

FIG. 9 is an enlarged view of a portion of FIG. 5.

FIG. 10 is a top perspective view of another embodiment of the heat sinkof FIG. 4.

FIG. 11 is a top plan view of the heat sink of FIG. 10.

FIG. 12 is a cross-sectional elevation view taken along the line 12—12in FIG. 11.

FIG. 13 is a side elevation view as viewed from the top of FIG. 11.

FIG. 14 is side elevation view as viewed from the right side of FIG. 11.

FIG. 15 is bottom plan view of the heat sink of FIG. 11.

FIG. 16 is a top perspective view of another embodiment of the coolingdevice of FIG. 3, mounted on the electronic package of FIG. 1.

FIG. 17 is a top plan view of a heat sink of the cooling device of FIG.16.

DETAILED DESCRIPTION OF THE INVENTION

FIGS. 3-17, in general, illustrate a cooling device 50 for dissipatingheat. Cooling device 50 may include a substantially planar surface 110;a chamber 120 having a first open end 118 and a second substantiallyclosed end 124; a heat conductive portion 104 extending between thechamber second closed end 124 and the planar surface 110 and a chamberwall member 114 substantially surrounding the chamber 120. The chamberwall member may include a first lobe 150 comprising an enlarged portionof the chamber wall member 114; a second lobe 170 including an enlargedportion of the chamber wall member 114 and a recessed area 152 locatedbetween the first lobe 150 and the second lobe 170. The recessed area152 may include a smaller portion of the chamber wall member 114relative to the first lobe 150 and the second lobe 170. The first lobe150 may be larger than the second lobe 170.

FIGS. 3-17 further illustrate, in general, a cooling device 50 forcooling a component 10 having a first heat generating area 40 and asecond heat generating area 42 which is spaced a first distance from thefirst heat generating area 40. The cooling device 50 may include aplurality of vanes 220 having slots 200 extending therebetween. Theplurality of vanes 220 may define an external periphery 102 of thecooling device 50. The external periphery 102 may include a firstoutwardly extending lobe 150 and a second outwardly extending lobe 170.The second outwardly extending lobe 170 may be spaced the first distancefrom the first outwardly extending lobe 150.

FIGS. 3-17 further illustrate, in general a cooling assembly including aheat source 10 and a cooling device 50. The heat source 10 may include afirst heat emitting area 40 and a second heat emitting area 42distinctly located with respect to the first heat emitting area 40. Thecooling device 50 may include a plurality of vanes 220 having slots 200extending therebetween. The plurality of vanes 220 may define anexternal periphery 102 of the cooling device 50. The external periphery102 may include a first outwardly extending lobe 150 and a secondoutwardly extending lobe 170. The first outwardly extending lobe 150 maybe located adjacent the first heat emitting area 40.

Having thus described the apparatus in general, it will now be describedin further detail.

For purposes of the description set forth herein, unless otherwisespecified, certain directional terms shall, when used herein, have themeanings set forth below. The terms “radial” and “radially” are withreference to the axis B—B, e.g., FIG. 4, and generally refer todirections normal to this axis. The terms “up”, “upper”, “upwardly” andthe like refer the direction indicated by the arrow 14, FIG. 6. Theterms “down”, “lower”, “downwardly” and the like refer to the directionindicated by the arrow 16, FIG. 6.

The above terms are defined for illustration purposes only. In actualuse, the cooling device described herein may be mounted in any position,thus making terms such as “up” and “down” relative to the orientation ofthe cooling device.

FIGS. 1 and 2 illustrate an electronic device package 10. Electronicdevice package 10 may include a housing 20 which, in turn, may include abody portion 22, FIG. 1, and a cover portion 24. Cover portion 24 mayhave an upper surface 26 and an oppositely disposed lower surface, notshown. Threaded openings 28, 30, 32, 34 may also be formed in the coverportion 24.

Electronic device housing 20 may enclose a plurality of electronicdevices, not shown, in a conventional manner. Housing 20 may, forexample, be formed of a plastic material. Housing cover portion 24 maybe made of a heat conductive material, such as aluminum, and may be incontact with at least some of the plurality of the electronic deviceshoused within the housing 20. In this manner, heat generated by theelectronic devices may be transferred into the cover portion 24. Thistransfer of heat causes areas of heat concentration to be formed withinthe cover portion 24. Specifically, areas of heat concentration 40, 42and 44 may be formed, as illustrated in FIG. 1.

Heat concentration area 40, for example, may be caused by a firstelectronic device, e.g., a central processor chip, located directlybeneath the area 40 and in contact with the cover portion 24. In thismanner, heat from the first electronic device is conducted into thecover portion causing a concentration of heat in the area 40 of thecover portion 24.

Heat concentration area 42, for example, may be caused by a secondelectronic device, e.g., a cache RAM chip, located directly beneath thearea 42 and in contact with the cover portion 24. In this manner, heatfrom the second electronic device is conducted into the cover portioncausing a concentration of heat in the area 42 of the cover portion 24.

Heat concentration area 44, for example, may be caused by a thirdelectronic device which may, for example, be another cache RAM chip,located directly beneath the area 44 and in contact with the coverportion 24. In this manner, heat from the third electronic device isconducted into the cover portion causing a concentration of heat in thearea 44 of the cover portion 24.

In the example listed above, heat concentration area 40 is caused by acentral processing chip, whereas the heat concentration areas 42 and 44are each caused by cache RAM chips. Since a central processor chip willgenerally generate more heat than will a cache RAM chip, the heatconcentration area 40 may be significantly hotter than either of theheat concentration areas 42, 44.

Electronic device package 10 may, for example, be of the typecommercially available from INTEL Corporation and sold as a “PENTIUM IIXEON” Processor.

As discussed previously, it is desirable to use cooling devices toremove heat from electronic devices, such as those contained in theelectronic package 10, during operation in order to prevent damage tothe electronic devices and to enhance their operation. As also discussedpreviously, in order to effectively remove heat from a multipleelectronic device package, such as the electronic device package 10, ithas generally been necessary to provide a large cooling device which iscapable of contacting, or being in close proximity to, all of theelectronic devices within the package. Such large cooling devices,however, are problematic in that they are expensive and ofteninefficient.

Referring now to FIG. 3, an improved cooling device 50, which overcomesthe above problems, is shown mounted to the upper surface 26 of theelectronic device package cover portion 24. Generally, cooling device 50may include a fan 60 mounted within a heat sink 100. Heat sink 100 mayinclude a plurality of outwardly extending lobes 150, 170, 190. Arecessed area 152 may be located between the lobes 150 and 170; arecessed area 172 may be located between the lobes 170 and 190 and arecessed area 192 may be located between the lobes 190 and 150. As canbe appreciated, when the cooling device 50 is mounted to the uppersurface 26 of the electronic device package cover portion 24, asillustrated in FIG. 3, the lobe 150 will be in direct contact with theheat concentration area 40, FIG. 1; the lobe 170 will be in directcontact with the heat concentration area 42 and the lobe 190 will be indirect contact with the heat concentration area 44. In this manner, thecooling device 50 provides additional heat sink material, via the lobes150, 170, 190, in the specific locations where heat removal from theelectronic device package 10 is required, i.e., the heat concentrationareas 40, 42, 44, respectively. Conversely, heat sink material isomitted in areas where heat removal from the electronic device package10 is not required, i.e., in the area of the recesses 152, 172, 192where no heat concentration areas are located.

The cooling device 50 will now be described in further detail. Referringagain to FIG. 3, the fan 60 may be rotatable about a fan rotation axisA—A. The fan 60 may be driven by a 12 volt DC brushless motor. Fan 60may, for example, be of the type commercially available from MatsushitaElectric Company of Japan, sold as Model FBA06T12H and under thetradename “PANAFLO” (with its housing removed). Fan 60 may have a height(measured along the axis A—A) of about 14 mm and a diameter (at the tipsof the fan blades) of about 56 mm.

FIGS. 4-9 illustrate the cooling device heat sink 100 in further detail.Heat sink 100 may include a substantially planar bottom surface 110,FIGS. 5-8, which is adapted to contact the upper surface 26 of theelectronic package cover portion 24 when the heat sink 100 is mounted tothe electronic package 10 as shown in FIG. 3. Referring to FIGS. 4-8,the heat sink 100 may include a central axis B—B which extends in aperpendicular manner relative to the bottom surface 110. When the fan 60is installed within the heat sink 100, as illustrated, for example, inFIG. 3, the fan rotation axis A—A will be superimposed on the heat sinkcentral axis B—B.

Referring to FIGS. 4 and 5, a fan chamber 120 may be provided as shown.Fan chamber 120 may be generally cylindrical in shape and may be adaptedto receive the fan 60 in a manner as shown in FIG. 3. A plurality ofslots 200, such as the individual slots 202, 204, 206, 208, 214, mayextend radially outwardly from the fan chamber 120 to the outerperiphery 102 of the heat sink 100. A plurality of cooling vanes 220,such as the individual cooling vanes 222, 224, 226, 228, 234 may alsoextend radially outwardly from the fan chamber 120 to the outerperiphery 102. As can be appreciated, one of the cooling vanes 220 willextend between every two of the slots 200 as illustrated, for example,with reference to the cooling vane 222 extending between the slots 202and 204 and the cooling vane 224 extending between the slots 204 and206.

As can be appreciated, each of the cooling vanes 220 will have aradially inner face and a radially outer face. With reference to FIGS. 4and 5, the vane 228, for example, will have a radially inner face 230and a radially outer face 232. As can further be appreciated, theradially outer faces of all of the vanes 220, e.g., the radially outerface 232 of the vane 228, together, form the outer periphery 102 of theheat sink 100. In a similar manner, the radially inner faces of all ofthe vanes 220, e.g., the radially inner face 230 of the vane 228,together, form a generally annular “surface” 122, FIG. 5, which definesthe radially outer periphery of the fan chamber 120. Outer surface 122may be formed at a radius of about 29 mm from the heat sink central axisB—B. With reference to FIG. 4, the width of the slots (as measured in adirection normal to the radial direction) may be substantially constantalong their length. As a result, each of the vanes 200 may be thicker atthe heat sink outer periphery 102 than at the fan chamber outer surface122. As can be appreciated, at the outer periphery 102 of the heat sink100, the vanes 200 in the lobes 150, 170, 190 will be thicker than thevanes in the recesses 152, 172, 192 due to the fact that the vanes 200in the lobes have longer radial lengths than do those in the recesses.

With reference to FIGS. 4 and 5, the vanes 220 generally define a wallportion 114 extending between the fan chamber outer surface 122 and theouter periphery 102 of the heat sink 100. Referring for example to FIGS.5-7, the vanes 220 may include a rounded profile 280 in the area of thelobes 150, 170, 190. The vanes 220 may also have an upper relativelyflat surface 282 which may be substantially parallel to the heat sinkbottom surface 110 and a relatively vertical surface 284 which may besubstantially perpendicular to the bottom surface 110. With reference toFIG. 6, heat sink 100 may, for example, have a height “o” of about 34.5mm extending between the heat sink bottom surface 110 and the uppersurface 282 of the vanes 220 and a width “y” of about 102.7 mm extendingbetween the lobes 170 and 190 at the outer periphery 102.

Referring again to FIGS. 4 and 5, fan chamber 120 may also include abottom surface 124. A heat conductive base portion 104 may extendbetween the fan chamber bottom surface 124 and the heat sink bottomsurface 110. As best shown in FIG. 5, fan chamber bottom surface 124 maybe formed at an angle “a” relative to the heat sink bottom surface 110and, thus, may taper toward the bottom surface 110 in a radially outwarddirection. This tapering away of the fan chamber bottom surface 124 hasbeen found to reduce noise generated by the cooling device 50 when inoperation. Specifically, the tapered configuration of the surface 124causes the spacing between the surface 124 and the lower edge of theblades of the fan 60 to increase in a radially outward direction. As canbe appreciated, radially outward portions of the fan blades will rotateat a higher velocity relative to radially inward portions of the fanblades. The tapered configuration of the surface 124, thus, causes thesurface 124 to be spaced further from the lower edge of the fan bladesin locations where the fan blades are moving at a higher velocity. This,in turn, has been found to reduce the noise generated by the fan 60 whenin operation. To achieve adequate noise reduction, the angle “a” shouldbe between about 15 and about 25 degrees. Most preferably, the angle “a”should be about 20 degrees.

Referring to FIGS. 4 and 5, a generally cylindrical recess 126 may becentrally formed in the fan chamber bottom surface 124 as shown. Recess126 may be formed at a radius of approximately 18.6 mm about the axisB—B and may extend for a depth “b” of about 8.0 mm below the fan chamberlower surface 124. Recess 126 may include an annular lower surface 128and a generally cylindrical sidewall surface 130 extending between thefan chamber bottom surface 124 and the recess lower surface 128. Lowersurface 128 may be substantially parallel to the heat sink bottomsurface 110.

A further recess 132 may be centrally formed in the lower surface 128 ofthe recess 126 as shown. Recess 132 may be formed at a radius of about14.8 mm about the axis B—B and may extend for a depth “c” of about 11.2mm below the lower surface 128 of the recess 126. Recess 132 may includea generally circular lower surface 134 and a generally cylindricalsidewall surface 136 extending between the lower surface 128 of therecess 126 and the lower surface 134. The lower surface 134 of therecess 132 may be spaced a distance “d” of about 2.5 mm from the heatsink bottom surface 110 and may be substantially parallel thereto.

The recesses 126 and 132, as described above, may be provided tofacilitate mounting of the fan 60 within the heat sink chamber 120.Specifically, when the fan 60 is inserted into the heat sink 100, asshown in FIG. 3, the base member of the fan 60 may be retained withinthe recesses 126. The fan may, for example be secured to the lowersurface 128 of the recess 126 with a conventional adhesive. Such anadhesive may be applied to either the base member of the fan 60 or tothe lower surface 128 of the heat sink recess 126 or to both.Alternatively, the fan 60 may be secured within the heat sink 100 in anyconventional manner.

As can be appreciated, mounting the fan 60 in the manner described abovewill result in an open cylindrical space, i.e., the recess 132, beinglocated beneath the base of the fan 60. This open space may be providedin order to insulate the motor of the fan 60 from the heat sink base 104and, thus, reduce the amount of heat which transfers from the base 104to the fan motor. This is advantageous since it has been found thatsubjecting a fan motor to excessive heat tends to degrade the operationand life of the fan motor. The open space formed by the recess 132, asdescribed above, also reduces the amount of material used to form theheat sink 100 and, thus, the overall weight of the heat sink.

Referring again to FIGS. 4 and 5, each of the slots 200 may extend intothe heat sink base portion 104 and intersect the fan chamber bottomsurface 124 in an upwardly facing opening. The slots 202, 204, 206 and208, for example, intersect the fan chamber bottom surface 124 inupwardly facing openings 203, 205, 207, 209, respectively, asillustrated in FIG. 4. Each slot may include a lower surface whichtransitions from the maximum height of the fan chamber bottom surface124 to a height “e”, FIG. 5, of about 2.5 mm above the heat sink bottomsurface 110. With respect, for example, to the slot 208, FIG. 5, acurved portion 210 may extend downwardly from the fan chamber bottomsurface 124 and may intersect with a substantially flat portion 212which may be substantially parallel to the heat sink bottom surface 110.Curved portion 210 may, for example, be formed at a radius of betweenabout 37.5 mm and about 76.0 mm. Preferably, the radius may be about50.4 mm. It is noted that the heat sink wall portion 114 is thinner(i.e., has a smaller radial extent) in the recessed areas 152, 172, 192than it is in the lobes 150, 170, 190. Accordingly, the length (i.e.,the radial extent) of the slot flat portion, e.g. the flat portion 212of the slot 208, may be less in the recessed areas than in the lobes.

Referring now to FIG. 6, it can be seen that each of the slots 200 mayhave a rounded bottom profile as illustrated, for example, with respectto the rounded bottom profile 216 of the slot 214. This rounded profileimproves the manufacturability of the heat sink 100, for example, whenthe heat sink is formed in a casting process. The rounded profilefurther enhances the heat transfer efficiency of heat with respect tothe vanes 220.

Referring again to FIG. 6, each of the slots may also increase in widthtoward its upper end. Referring again to FIG. 6, it can be seen that theslot 214, for example, includes a draft angle “f” of about 1.5 degrees.This draft angle facilitates the manufacturability of the heat sink 100.Specifically, when manufacturing the heat sink 100, e.g., via a castingor forging operation, the draft angle “f” facilitates removal of theheat sink from the mold or casting. The draft angle “f” also increasesthe efficiency of the cooling vanes 220 with respect to the transfer ofheat from the vanes 220 into the surrounding ambient air. The draftangle “f” further improves the aerodynamics of the heat sink withrespect to air flowing through the slots 200.

Referring again to FIG. 4, heat sink 100 may include mounting feet 240,250, 260 and 270. The mounting feet 240 and 250 may extend outwardlyfrom the lobes 170, 190, respectively. The mounting feet 260, 270 mayextend outwardly from the lobe 150. The mounting feet 240, 250, 260, 270may include holes 242, 252, 262, 272, respectively, extendingtherethrough. Each hole may have a diameter of about 3.7 mm. Withreference to FIG. 3, in order to attach the cooling device 50 to theelectronic device package 10, screws 248, 258, 268, 278 may be passedthrough the heat sink holes 242, 252, 262, 272, respectively and engagedwithin the threaded openings 28, 30, 32, 32, respectively, in theelectronic package cover portion 24, FIG. 1. As illustrated, e.g., inFIG. 3, the mounting feet 240, 250, 260, 270 may have relatively flatupper surfaces, such as the flat upper surface 264 of the foot 260, FIG.3. Alternatively, the upper surfaces of the mounting feet 240, 250, 260,270 may have a domed profile in order to facilitate themanufacturability of the heat sink 100, e.g., via a casting or forgingprocess. Such a domed profile also adds rigidity to the mounting feet240, 250, 260, 270.

FIG. 9 is an enlarged view of the foot 270 as illustrated in FIG. 5. Ascan be seen with reference to FIG. 9, the foot 270 may include anundercut surface 274 which may be spaced a distance “g” of about 0.5 mmfrom the heat sink bottom surface 110. Undercut surface 274 may beconnected to the heat sink bottom surface 110 via a substantiallyvertical surface 276. Surface 276 may be formed at a radius “v” of about60.0 mm from the axis B—B, as illustrated in FIG. 8. As can beappreciated, the undercut surface 276 will be spaced from the uppersurface 26 of the electronic device package cover portion 24 when thecooling device 50 is mounted thereto, FIG. 3. This space allows the foot270 to be deflected downwardly due to the tightening torque applied tothe screw 278. This downward deflection, in turn, provides an upwardforce on the head of the screw 278 and tends to prevent loosening of thescrew after it is tightened. This deflection also tends to ensurepositive and reliable contact between the bottom surface 110 of the heatsink 100 and the upper surface 26 of the electronic device package 10.Each of the other feet 240, 250 and 260 may include an undercut surfaceidentical to that described above with respect to the foot 270.

In operation, when the cooling device 50 is mounted to the electronicdevice package 10, as illustrated in FIG. 3, heat from heatconcentration area 40, FIG. 1, will be conducted into the heat sink baseportion 104 in the vicinity of the lobe 150. From there, the heat isconducted into the vanes 220 located within the lobe 150 and, to alesser extent, into the remainder of the heat sink 100. In a similarmanner, heat from heat concentration areas 42 and 44 will be conductedinto the heat sink base portion 104 in the vicinity of the lobes 170,190, respectively. From there, the heat is conducted into the vanes 220located within the lobes 170, 190, respectively and, to a lesser extent,into the remainder of the heat sink 100.

In this manner, heat is conducted away from the heat concentration areas40, 42 and 44. It is noted that it is advantageous to provide a heatsink having multiple lobes, as described above, as opposed to providingseparate cooling devices for each heat concentration area to be cooled.This is because, in the heat sink having multiple lobes, each lobe tendsto assist the other lobes in removing heat from the heat source. Thelobe 170, for example, primarily serves to cool the heat concentrationarea 42. Because the lobe 170 is thermally connected to the lobes 150and 190, however (via the recessed portions 152 and 172, respectively),the lobe 170 also tends to draw heat away from the heat concentrationareas 40 and 44 and, thus, assist the lobes 150 and 190 in cooling theheat concentration areas 40 and 44, respectively.

To facilitate heat transfer between the upper surface 26 of theelectronic package cover portion 24 and the cooling device 50, a heatconductive substance, such as a heat conductive grease, may be appliedbetween the upper surface 26 of the electronic package cover portion 24and the bottom surface 110 of the cooling device 50.

For efficient cooling, the heat, after being transferred into the heatsink base portion 104 and vanes 220 must be further transferred into thesurrounding air. The ability of a heat sink device, such as the heatsink 100, to transfer heat into the air depends, among other things,upon the amount of surface area of the heat sink device exposed to thesurrounding air. The cooling vanes 220 facilitate such heat transfer byeffectively increasing the surface area of the heat sink device 100.

In operation, fan 60 may rotate in a counter-clockwise direction, asviewed, for example, in FIG. 3. Referring to FIG. 7, thiscounter-clockwise fan rotation will cause air movement in the generaldirection of the arrows 138, 139. Specifically, intake air from theexterior of cooling device 50 will enter the heat sink fan chamber 120through the open upper end 118 of the fan chamber 120. This air movementis indicated by the arrows 140, 142 in FIG. 7. After entering the fanchamber 120, the air moves downwardly, in a direction aligned with thearrows 138, 139 through the fan chamber 120 toward the fan chamberbottom surface 124, FIG. 5. Continuing its downward movement, the airenters the lower portion of the slots 200 through upwardly facingopenings of the slots, such as the upwardly facing opening 209, FIG. 5,in the fan chamber bottom surface 124. The air then travels down thelower portion of the slots 200, e.g, along the curved portion 210 andthe flat portion 212 of the slot 208, FIG. 5 and exhausts from thecooling device in a substantially horizontal flow path as indicated bythe arrows 144 and 146, FIG. 7.

As the air moves through the lower portion of the slots 200, asdescribed above, it also moves between the lower portions of theassociated vanes 220, located in the base portion 104, thereby coolingthe vanes and removing heat from the heat sink 100.

Referring again to FIG. 7, additional intake airflow paths are indicatedby the arrows 148 and 150. The airflow 148, 150 comprises air movingfrom the exterior of the cooling device 10, through the upper portion ofthe slots 200 and into the fan chamber 120. The airflow 148, 150 thenjoins the airflow 140, 142 to form the airflow 138, 139 previouslydescribed.

As the airflow 148, 150 moves through the upper portion of the slots200, as described above, it also moves between the upper portions of theassociated vanes 220, thereby providing additional cooling of the vanes71, and removal of heat from the heat sink assembly 50.

As can be appreciated from the above description, each vane 220 of theheat sink 100 is cooled by two separate airflows. First, airflow 148,150 moves past an upper portion of the vanes 220 to cool the vanes.Thereafter, the airflow 144, 146 moves past a lower portion of the vanes220 to further cool the vanes. Accordingly, a portion of the air movingthrough the cooling device 50 is used twice for cooling; once on intakemaking up the airflow 148, 150 and a second time on exhaust partiallymaking up the airflow 144, 146.

As previously described, the slots 220 in the heat sink assembly baseportion 104 define upwardly facing openings, e.g., the upwardly facingopening 209 of the slot 208, FIG. 5. These openings serve to provide anexhaust path for air exiting the fan chamber 120 during operation of thecooling device 50. The bottom portions of the slots 200 include curvedsurfaces portions, such as the curved portion 210 shown in FIG. 5. Thesecurved portions cause the airflow through the cooling device 50 tosmoothly transition from the vertical airflow path 138, 139 to thehorizontal exhaust flow path 144, 146 as described previously withreference to FIG. 8.

Referring now to FIG. 8, the specific shape and dimensions of the heatsink periphery 102 will now be described by way of example. A first axisC—C may be located as shown. First axis C—C intersects the axis B—B andis arranged at a right angle thereto. First axis C—C may further bechosen such that the heat sink periphery 102 is symmetrically arrangedrelative thereto. A second axis D—D may be formed at right angles to theaxis B—B and to the axis D—D. A point 300 may lie on the axis C—C adistance “h” of about 30.3 mm from the axis D—D as shown. A point 302may be located a distance “i” of about 22.4 mm from the axis D—D and adistance “j” of about 29.8 mm from the axis C—C, as shown. A point 304may be located the distance “i” from the axis D—D and a distance “k” ofabout 29.8 mm from the axis C—C.

In the area of the lobe 150, the outer periphery 102 of the heat sink100 may be formed having a radius “l” of about 28.4 mm from the point300, as shown in FIG. 8. In the area of the lobe 190, the outerperiphery 102 may be formed having a radius “m” of about 21.5 mm fromthe point 302. In the area of the lobe 170, the outer periphery 102 maybe formed having a radius “n” of about 21.5 mm from the point 304. Inthe recessed areas 152, 172, 192, the outer periphery 102 may be formedhaving a radius “o” of about 34.5 mm about the axis B—B.

As can be appreciated, the heat sink wall portion 114 extends betweenthe fan chamber outer surface 122 and the heat sink outer periphery 102.Accordingly, the wall portion 114 will be substantially thicker in thearea of the lobes 150, 170, 190 than in the area of the recesses 152,172, 192. As previously set forth, fan chamber outer surface 122 may beformed at a radius of about 29.0 mm from the heat sink central axis B—B.Given this radius, and the dimensions set forth above, the wall portion114 may have a maximum thickness of about 29.7 mm in the area of thelobes 150, 170 and 190. In the recessed areas 152, 172, 192, the wallportion 114 may have a substantially uniform thickness of about 5.5 mm.

Referring again to FIG. 4, heat sink 100 may have a width “p” of about90.7 mm extending between the centers of the holes 242, 252 and a length“q” of about 95.5 mm extending between the centers of the holes 242,272, as shown. Referring to FIG. 5, heat sink 100 may extend for adistance “r” of about 141.7 mm between the outer edges of the feet 250and 270. With further reference to FIG. 5, heat sink 100 may extend fora distance “s” of about 120 mm between the surface 276 of the foot 270and the corresponding surface of the foot 250, as shown. Referring toFIG. 6, the outer periphery 102 of the heat sink 100 may have a width“t” of about 102.7 mm extending between the lobes 170 and 190, as shown.Referring to FIG. 7, heat sink 100 may have a length “u” of about 111.5mm extending between the outer extent of the foot 250 and the heat sinkouter periphery 102 in the area of the lobe 150.

As mentioned previously, the heat sink 100 may be symmetrical about theaxis C—C, FIG. 8. Accordingly, the amount of heat sink mass located onone side of the axis C—C may be substantially equal to the amount ofheat sink mass located on the opposite side of the axis C—C. Althoughthe heat sink 100 is not symmetrically shaped about the axis D—D, thedimensions outlined above result in the amount of mass located on oneside of the axis D—D being substantially equal to the amount of masslocated on the opposite side of the axis D—D. This mass balance,relative to the axis D—D, results because the mass of the lobe 150 issubstantially equal to the combined mass of the lobes 170 and 190. Themass of the lobe 150 may, thus, be substantially larger than the mass ofeach of the lobes 170, 190. The lobe 150 may be provided having a largermass because the lobe 150 overlies the heat concentration area 40 of theelectronic device package 10, FIG. 1, which, as described previously, issignificantly hotter than either of the heat concentration areas 42, 44.

As can be appreciated from the above, the center of mass of the heatsink 100 will lie on the axis B—B, i.e., at the intersection of the axesC—C and D—D. This is an important feature of the heat sink 100 in thatthe center of mass of the heat sink is centrally located relative to thefan chamber 120 and relative to the rotational axis A—A of the fan 60.

As can be appreciated, the shape of the heat sink 100, specifically thesize and shape of the lobes 150, 170, 190, allows heat sink mass to beconcentrated in areas where cooling is required on the electronic devicepackage 10, e.g., the heat concentration areas 40, 42, 44, FIG. 1. Thisallows the heat sink 100 to be less massive, e.g., by omitting materialin the recessed areas 152, 172, 192, while still adequately cooling anelectronic device package.

It is noted that the specific electronic device package 10 and thecorresponding specific shape and size of the heat sink 100, includingthe shape, size and location of the lobes 150, 170, 190 have beendisclosed herein for exemplary purposes only. The heat sink 100 mayreadily be configured to correspond to the configuration of anyelectronic device package. The heat sink 100, for example, may readilybe reconfigured having a different number of lobes and/or havingdifferently shaped, sized or located lobes in order to correspond to anelectronic device package having a configuration of heat concentrationareas which is different from the exemplary configuration disclosed withreference to the electronic device package 10.

It is noted that the lobes 150, 170, 190 have been described herein asbeing substantially circular. Although this circular shape is highlydesirable, e.g., from a manufacturability standpoint, the lobes couldreadily be formed having other than substantially circular shapes whilestill providing the advantages disclosed herein. The lobes may, forexample, readily be formed having a rectangular or triangular shape.

Heat sink 100 may be constructed of any heat conductive material andmay, for example, be formed in a conventional casting or forgingprocess. Alternatively, heat sink 100 may be formed in a conventionalmachining process. Preferably, heat sink 100 may be formed from arelatively high thermal conductivity material, such as aluminum. An AB60aluminum, for example, may be used when the heat sink 100 is formed in acasting operation. A 6061 or 6063 aluminum may, for example, be usedwhen the heat sink 100 is formed in a machining operation.

FIGS. 10-15 illustrate an alternate embodiment of the cooling device 50previously described. Referring to FIG. 10, a heat sink 400 may beprovided as shown. Heat sink 400 may include a plurality of outwardlyextending lobes 450, 470, 490. A recessed area 452 may be locatedbetween the lobes 450 and 470; a recessed area 472 may be locatedbetween the lobes 470 and 490 and a recessed area 492 may be locatedbetween the lobes 490 and 450. The outer periphery 402, e.g., FIG. 15,of the heat sink 400 may be substantially identical to the outerperiphery 102 of the heat sink 100 previously described.

Referring to FIGS. 11 and 12, a fan chamber 420 may be provided asshown. A plurality of slots 500, such as the individual slots 502, 504,506, 508, may extend radially outwardly from the fan chamber 420 to theouter periphery 402 of the heat sink 400. A plurality of cooling vanes520, such as the individual cooling vanes 522, 524, 526, 534 may alsoextend radially outwardly from the fan chamber 420 to the outerperiphery 402. As can be appreciated, one of the cooling vanes 420 willextend between every two of the slots 400 as illustrated, for example,with reference to the cooling vane 422 extending between the slots 402and 404 and the cooling vane 424 extending between the slots 404 and406.

Heat sink 400 may be substantially identical to the heat sink 100previously described, except that the fan chamber 420 of the heat sink400 may include a widened portion as will now be described in detail.Referring to FIG. 12, the i-an chamber 420 may include an outer surface422 which, at its lower extent, may be substantially identical to theouter surface 122 of the fan chamber 120 of the heat sink 100 aspreviously described. At its upper extent, however, the outer surface422 may flare outwardly as shown. Specifically, this outward flaring maybe accomplished by providing a curved surface 456 on each of the vanes520. Curved surface 456 may have a radius of about 12 , mm and may begina distance “w” of about 14.5 mm above the bottom surface 410 of the heatsink 400.

The widened portion of the fan chamber 420, as described above, resultsin a plurality of openings being formed in the wall portion 414, FIG.12, of the heat sink 400. Specifically, the openings 454, 474, 494 maybe formed in the recessed areas 452, 472, 492, respectively, due to thereduced thickness of the wall portion 414 in those areas. As can beappreciated, with reference to FIG. 14, the carved surface 456 willcause the wall portion 414 to have a lower height “z” in the area of therecesses 454 474, 494. This relatively lower height “z” results in theopenings 454, 474, 494. The height “z” may, for example, be about 15.5mm.

It has been found that the provision of the openings 454, 474, 494, asdescribed above, allows the heat sink 400 to operate in low clearanceenvironments, e.g., an environment in which an adjacent electroniccomponent is in close proximity to the upper edge 582, FIG. 12, of theheat sink 400. In such a low clearance environment, air may besubstantially prevented from entering the fan chamber 420 via the openupper end 418 of the heat sink 400. The provision of the openings 454,474, 494, however, provides an alternate route for air to enter the fanchamber 420 and, thus, allows air to circulate through the heat sink400. The heat sink 400 may, thus, operate efficiently even in a lowclearance environment. It has been found, in fact, that the heat sink400, having the openings 454, 474, 494, will function even in anenvironment where there is no clearance above the heat sink upper edge582.

It is noted that, although a curved surface 456 is described above, awidened fan chamber may alternatively be provided by merely angling theouter surface 122 of the fan chamber 120. Specifically, the outersurface 122 may angle outwardly and upwardly such that the fan chamber120 is wider at its upper extent (i.e., near the open upper end 118 ofthe heat sink) than at its lower extent (i.e., near the bottom surface124 of the fan chamber). The outer surface 122 may, for example, beangled at an angle of about 20 degrees with respect to the vertical(i.e., with respect to the axis B—B.)

The widened portion of the fan chamber 420 also serves to space at leastportions of the outer surface 422 of the fan chamber 420 from the edgesof the fan blades when a fan, such as the fan 60 previously described,is inserted within the fan chamber 420. This spacing has been found toreduce the noise generated by the fan when in operation, withoutsignificantly reducing the heat removal ability of the heat sink 400.The widened portion also results in less heat sink material, relative tothe heat sink 100, and thus results in a less expensive and lighterweight heat sink relative to the heat sink 100.

Other than the provision of the widened fan chamber 420, as describedabove, the heat sink 400 may be formed and may function in an identicalmanner to the heat sink 100 previously described.

FIGS. 16 and 17 illustrate a further embodiment of the cooling device50. Referring to FIG. 16, a cooling device 650 may be provided mountedto the electronic device package 10. Cooling device 650 may include afan 660 housed within the fan chamber 720 of heat sink 700 in a mannersimilar to the fan 60 and the heat sink 100, previously described. Heatsink 700 may include a plurality of outwardly extending lobes andalternating recesses in a manner substantially identical to the heatsink 100. A plurality of slots 800, such as the individual slots 802,804, 806 may extend outwardly from the fan chamber 720 to the outerperiphery 702 of the heat sink 700. A plurality of cooling vanes 820,such as the individual cooling vanes 822, 824, 826 may also extendoutwardly from the fan chamber 720 to the outer periphery 702. As can beappreciated, one of the cooling vanes 820 will extend between every twoof the slots 800 as illustrated, for example, with reference to thecooling vane 824 extending between the slots 802 and 804.

Heat sink 700 may be substantially identical to the heat sink 100. Inthe heat sink 700, however, the slots 800 and vanes 820 are not radial,but, instead, are offset from the radial direction. Referring to FIG.17, it can be seen that the slots 800 and vanes 820 may be offset anangle “x” of about 8.0 degrees from the radial direction 890. Thisnon-radial configuration of the slots and vanes may be provided in orderto reduce the noise generated by the fan 660 when in operation.

Heat sink 700 may also differ from the heat sink 100 in that the heatsink 700 may be mounted to the electronic component 10 with a mountingbracket 900. Mounting bracket 900 may be configured to havesubstantially the same shape as the periphery 702 of the heat sink 700.Referring to FIG. 16, the bracket 900 may fit over the upper portion ofthe heat sink 700 and may be secured to the electronic package 10 viathreaded bolts 928, 930, 932, 934, as shown, engaged within theelectronic package threaded openings 28, 30, 32, 34, respectively, FIG.1.

Bracket 900 may be formed as a separate part from the heat sink 700. Inthis case, the heat sink 700 may be provided with a shoulder portion,not shown, to allow the bracket 900 to apply downward force to the heatsink 700 relative to the electronic package 10. Alternatively, thebracket 900 may be integrally formed with the heat sink 700 in, e.g., acasting process. In the case where the bracket 900 is integrally formedwith the heat sink 700, a fillet, or a plurality of fillets, not shown,may be provided at the lower juncture of the bracket 900 and the heatsink 700 in order to add strength and stability. The bracket 900 mayalso act as an air separator, thus preventing the recirculation of warmair about the exterior of the heat sink. The bracket 900 may, forexample, serve to physically separate the upper, intake air flow paths140, 142, FIG. 7, from the lower intake and exhaust airflow paths 144,146, 148, 150.

Other than for the provision of the non-radial slots and vanes and thebracket mounting arrangement, as described above, the heat sink 700 maybe formed and may function in an identical manner to the heat sink 100previously described.

While an illustrative and presently preferred embodiment of theinvention has been described in detail herein, it is to be understoodthat the inventive concepts may be otherwise variously embodied andemployed and that the appended claims are intended to be construed toinclude such variations except insofar as limited by the prior art.

What is claimed is:
 1. A cooling device for dissipating heat, saidcooling device comprising: a substantially planar surface; a chamberhaving a first open end and a second substantially closed end; a heatconductive portion extending between said chamber second closed end andsaid planar surface; a chamber wall member substantially surroundingsaid chamber, wherein said chamber wall member includes: a firstprotrusion comprising an enlarged portion of said chamber wall member; asecond protrusion comprising an enlarged portion of said chamber wallmember; a recessed area located between said first protrusion and saidsecond protrusion, said recessed area comprising a smaller portion ofsaid chamber wall member relative to said first protrusion and saidsecond protrusion; and wherein said first protrusion is larger than saidsecond protrusion.
 2. The cooling device of claim 1 and furtherincluding a plurality of slots extending through said chamber wallmember.
 3. The cooling device of claim 2 wherein said plurality of slotscommunicate with said chamber.
 4. The cooling device of claim 2 whereinsaid plurality of slots are arranged in a generally radialconfiguration.
 5. The cooling device of claim 1 wherein said chamberwall member further includes: a third protrusion comprising an enlargedportion of said chamber wall member.
 6. The cooling device of claim 5wherein said third protrusion is smaller than said first protrusion. 7.The cooling device of claim 5 wherein said chamber wall member furtherincludes: a second recessed area located between said first protrusionand said third protrusion, said second recessed area comprising asmaller portion of said chamber wall member relative to said first,second and third protrusions.
 8. The cooling device of claim 1 andfurther including a fan located in said chamber.
 9. The cooling deviceof claim 1 wherein said chamber is substantially cylindrically formedabout a cooling device central axis.
 10. The cooling device of claim 9wherein said chamber second substantially closed end slopes toward saidsubstantially planar surface in a radial outward direction relative tosaid cooling device central axis.
 11. The cooling device of claim 9wherein said cooling device has a center of mass and wherein said centerof mass is located along said cooling device central axis.
 12. Thecooling device of claim 1 and further comprising: a cooling devicecentral axis extending normal to said substantially planar surface;wherein said chamber has a first width, measured normal to said centralaxis, at a first distance from said substantially planar surface;wherein said chamber has a second width, measured normal to said centralaxis, at a distance from said substantially planar surface that isgreater than said first distance; and wherein said second width isgreater than said first width.
 13. The cooling device of claim 1 whereinsaid first protrusion has a generally rounded profile.
 14. A coolingdevice for cooling a component having a first heat generating area and asecond heat generating area spaced a first distance from said first heatgenerating area, said cooling device comprising: a plurality of vaneshaving slots extending therebetween; said plurality of vanes defining anexternal periphery of said cooling device; said external peripheryincluding a first outwardly extending protrusion and a second outwardlyextending protrusion; wherein said second outwardly extending protrusionis spaced said first distance from said first outwardly extendingprotrusion; a chamber substantially cylindrically formed about a centralaxis of said cooling device; and a fan located in said chamber.
 15. Theapparatus of claim 14 wherein said component includes a third heatgenerating area spaced a third distance from said first heat generatingarea and wherein said cooling device further comprises: said externalperiphery including a third outwardly extending protrusion; wherein saidthird outwardly extending protrusion is spaced said third distance fromsaid first outwardly extending protrusion.
 16. The cooling device ofclaim 13 wherein said first outwardly extending protrusion has agenerally rounded profile.
 17. The cooling device of claim 14 whereinsaid slots communicate with said chamber.
 18. The cooling device ofclaim 13 wherein said slots are arranged in a generally radialconfiguration.
 19. The cooling device of claim 13 wherein said secondoutwardly extending protrusion is smaller than said first outwardlyextending protrusion.
 20. The cooling device of claim 14 wherein saidthird outwardly extending protrusion is smaller than said firstoutwardly extending protrusion.
 21. The cooling device of claim 13wherein said cooling device includes a substantially planar surface andwherein said chamber includes a first open end a second substantiallyclosed end.
 22. The cooling device of claim 21 wherein said chambersecond substantially closed end slopes toward said planar surface in aradially outward direction relative to said cooling device central axis.23. The cooling device of claim 13 wherein said cooling device has acenter of mass and wherein said center of mass is located along saidcooling device central axis.
 24. A cooling assembly comprising: a heatsource including: a first heat emitting area; a second heat emittingarea distinctly located with respect to said first heat emitting area; acooling device including: a plurality of vanes having slots extendingtherebetween; said plurality of vanes defining an external periphery ofsaid cooling device; said external periphery including a first outwardlyextending protrusion and a second outwardly extending protrusion;wherein said first outwardly extending protrusion is located adjacentsaid first heat emitting area; said heat source further includes a thirdheat emitting area distinctly located with respect to said first heatemitting area and said second heat emitting area; said cooling deviceexternal periphery further includes a third outwardly extendingprotrusion; and wherein said third outwardly extending protrusion islocated adjacent said third heat emitting area.
 25. The cooling assemblyof claim 24 wherein said second outwardly extending protrusion islocated adjacent said second heat emitting area.
 26. The coolingassembly of claim 24 wherein said cooling device is attached to saidheat source.
 27. The cooling assembly of claim 24 wherein said firstoutwardly extending protrusion has a generally rounded profile.
 28. Thecooling assembly of claim 24 wherein said cooling device furtherincludes a chamber therewithin formed substantially cylindrically abouta cooling device central axis.
 29. The cooling assembly of claim 28wherein said cooling device has a center of mass and wherein said centerof mass is located along said cooling device central axis.
 30. Thecooling assembly of claim 28 wherein said plurality of slots communicatewith said chamber.
 31. The cooling assembly of claim 24 wherein saidslots are arranged in a generally radial configuration.
 32. The coolingassembly of claim 24 wherein said first outwardly extending protrusionis larger than said second outwardly extending protrusion.
 33. Thecooling assembly of claim 28 and further including a fan located in saidchamber.
 34. The cooling assembly of claim 28 wherein: said coolingdevice includes a substantially planar surface; said fan chamberincludes a first open end and a second substantially closed end; andwherein said chamber second substantially closed end slopes toward saidplanar surface in a radial outward direction relative to said coolingdevice central axis.